Acceleration stumble at highway speed Help!

[daytona90t]

I started this post back in April and finally found the correct solution this past weekend, pre-cat O2 sensors. I have posted my solution below and if you scan through the entire thread (only 6 pages) you can see what I tried, replaced, checked, tested, and what didn't work and what did. My eventual conclusion is that If you have had your DME updated, or verified that you already have the most up to date software revision, and even if you don't have a code indicating a bad O2 sensor, replace your pre-cat O2 sensors.

Post#56 with solution.

It seems that I have finally had success at solving this issue. I replaced both pre-cat O2 sensors this morning with the Bosch 17215, re-set DME adaptations, and took the car for a drive. The car seems to be completely cured of the 2,800 rpm stumble/hesitation issue and feels more responsive and eager to pull all the way through the rev range than I have ever experienced. After 6 months of researching, replacing a bunch of parts, and verifying that I already had the most up to date DME software revision, it seems to have been a degraded pre-cat O2 sensor all along. I never had a check engine light, or even a code until last weekend.

Hopefully my experience can help someone else on here from going completely insane trying to cure this issue. If you have had your DME updated, or verified that you already have the most up to date software revision, and even if you don't have a code indicating a bad O2 sensor, replace your pre-cat O2 sensors.

1st Post from April.

Hi Everyone,

I am hoping that someone on here can point me in the right direction for the issue that I seem to be having. 2004 zhp auto with 105,000. About 2 weeks ago I started to notice a high speed acceleration stumble when I am trying to accelerate from a cruising speed of around 70. The car has near perfect smooth power throughout the whole range up till this point but if I ask a little more of it there is a noticeable stumble like it is being starved for fuel or has a bad misfire. It will eventually get to where I am asking it to go but not without a stumbling jerking feeling throughout the whole car. Verified by cruising at about 70 then opening up the throttle to accelerate up to 90, it will get there but it doesn’t seem to like it. It is fine around town and will only give me this problem on the highway. Since this probably has more to do with cruising rpm than speed, at these speeds in 5th rpm is around the 3,000 range or a little over. My wife says that I should just slow down but there is obviously a bigger issue here.

Maintenance in the last 20,000 miles includes: fuel pump, fuel filter, spark plugs, silicone intake boot, rebuilt DISA with GAS kit, rebuilt VANOS with Beisan Systems seals. Valve cover gasket, and probably a few other things I am forgetting. I am thinking possible causes could be O2 Sensor, camshaft position sensor, VANOS solenoid, coil pack, vacuum leak? I have no codes and no issues in the lower power range.

Any more solid ideas would be greatly appreciated?

[ZHPizza]

Do you have the OE airbox or something else? I remember seeing some people with CAI's speak of stumbling issues at highway speeds.

[daytona90t]

Hi,

Yes I have the OE airbox with a K&N air filter and the mishimoto silicon intake boot.

[san]

I would've thought fuel filter or maybe fuel pump but seems like you replaced them recently so I'm not really sure. My next guess is the cam position sensor but that's just me guessing...


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[BADCLOWN]

Bad coil pack/spark plug

[anandoc]

I have a auto 330i as well and I have a slight hesitation at around 2800 RPM...usually quite evident when I am cruising along on the highway and I suddenly need to accelerate. But I don't get jerking throughout the car.

What if you put it in M/S mode and then downshift to 4th and try to accelerate? This would validate whether the issue only happens at that specific RPM range or not...

[daytona90t]

On the ride home from work today I realized that at 70-80 mph the rpms are closer to 2,500-3,000, so right around the 2,800 rpm hesitation that anandoc has mentioned. Since I am so ridiculously meticulous with my cars anything that I can feel in my seat I consider the whole car. In reality it is more of a hesitation/stumble at or around 2,800 rpm at cruising speed. It could be there in other gears too, but is not as noticeable if it is.

anandoc, have you always had this 2,800 hesitation? I definitely didn't have this prior to a few weeks ago. I will try getting it to kick down to 4th or manually downshift tomorrow to see if I notice anything different.

I am leaning towards a bad coil pack as suggested by BADCLOWN, as I would think that any bad sensors would throw a code.

Hopefully we can pin point this issue and the information can help someone else as well. It looks like I may not be the only one with this issue.

[anandoc]

On the ride home from work today I realized that at 70-80 mph the rpms are closer to 2,500-3,000, so right around the 2,800 rpm hesitation that anandoc has mentioned. Since I am so ridiculously meticulous with my cars anything that I can feel in my seat I consider the whole car. In reality it is more of a hesitation/stumble at or around 2,800 rpm at cruising speed. It could be there in other gears too, but is not as noticeable if it is.

anandoc, have you always had this 2,800 hesitation? I definitely didn't have this prior to a few weeks ago. I will try getting it to kick down to 4th or manually downshift tomorrow to see if I notice anything different.

I am leaning towards a bad coil pack as suggested by BADCLOWN, as I would think that any bad sensors would throw a code.

Hopefully we can pin point this issue and the information can help someone else as well. It looks like I may not be the only one with this issue.

Pretty sure what you are describing is the infamous 2800 RPM hesitation on our cars. I've read that this can be fixed with a DME update. Some threads where you can read about this:

http://www.zhpmafia.com/forums/showthread.php?3171-Hesitation-during-acceleration

http://forum.e46fanatics.com/showthread.php?t=966614

[daytona90t]

Pretty sure what you are describing is the infamous 2800 RPM hesitation on our cars. I've read that this can be fixed with a DME update. Some threads where you can read about this:

http://forum.e46fanatics.com/showthread.php?t=966614

anandoc, Thank you so much for posting this link from e46fanatics. This seems to be my exact issue. The strange thing is that I have had the car for 4 years and never really noticed the issue until a few weeks ago. I wonder if it is possible that rebuilding the VANOS can exasperate the the problem and make it more noticeable. I did rebuild the VANOS last fall and then put my snow tires on shortly after. I usually drive the car much more conservatively with the snows, and didn't really notice the hesitation/stumble until I put my summer tires back on a few weeks ago.

I am going to read through the entire thread and possibly still replace my coil packs as they now have 105,000 on them and I don't think it could hurt, plus FCPEuro has them on sale right now. I am also going to check my DME software version to determine if it is the original tune. Would anyone happen to know the latest software version available to us? or at least which version corrects this problem?

Thank you for the help! I will make sure to keep you all updated as to my progress, also still open to any further suggestions.

[anandoc]

Keep us posted - I too am interested in addressing this issue.

[slater]

Pretty sure what you are describing is the infamous 2800 RPM hesitation on our cars. I've read that this can be fixed with a DME update.

i think it can be, and my ZHP suffers from the same thing. when the drivetrain goes in the Touring, i'll be flashing the Touring ECU with the latest revision (or the exact revision created to fix this issue).

[anandoc]

i think it can be, and my ZHP suffers from the same thing. when the drivetrain goes in the Touring, i'll be flashing the Touring ECU with the latest revision (or the exact revision created to fix this issue).

Guess who would be making a second trip to Picton? :)

[slater]

Guess who would be making a second trip to Picton? :)

LOL! :)

[ELCID86]

Have you tried unplugging the DISA wire plug and see if it performs better?

[daytona90t]

Have you tried unplugging the DISA wire plug and see if it performs better?

No I haven't. I thought about trying that though. I did rebuild the DISA about 2 years ago with the GAS kit, but I have heard that the vacuum diaphragm can fail as well.

[ELCID86]

Humor me and try it. I had a really bad stutter on acceleration and unplugging the DISA made it go away.

[daytona90t]

After verifying no change with DISA unplugged I checked my DME software version. I have SW-V5.1 version 7561382 with a build date of 05.08.2003. Since this is far from what should be the latest DME software version 7561520, I called my local dealership and spoke with the service manager. I am brining the car in in a few weeks for a DME and trans software update. They quoted me $145.00 to check and update the software. They said it should only take about an hour but set me up with a loaner just in case they don't get to it right away or in case the updates take longer. With service like that I cant complain about the quoted price. Part of me wants to hang around the dealership to make sure it goes smoothly, the rest of me wants to put some miles on the loaner. I will keep everyone up to date as to the outcome.

[ZHPizza]

After verifying no change with DISA unplugged I checked my DME software version. I have SW-V5.1 version 7561382 with a build date of 05.08.2003. Since this is far from what should be the latest DME software version 7561520, I called my local dealership and spoke with the service manager. I am brining the car in in a few weeks for a DME and trans software update. They quoted me $145.00 to check and update the software. They said it should take only take about an hour but set me up with a loaner just in case they don't get to it right away or in case the updates take longer. With service like that I cant complain about the quoted price. Part of me wants to hang around the dealership to make sure it goes smoothly, the rest of me wants to put some miles on the loaner. I will keep everyone up to date as to the outcome.
That sounds very reasonable. I bet they have cookies in the waiting area too.

[BMWCurves]

I always drive the loaner. Makes me appreciate my ZHP every time I step out of current BMWs and back into my ZHP.

EDIT: ZHPizza's right. Grab a cookie and coffee, then hoon the loaner.

[ELCID86]

Sorry that didn't help. About 1 hour of labor sounds about right. I hope that sorts it.

[daytona90t]

That sounds very reasonable. I bet they have cookies in the waiting area too.

BMW of Sudbury is really fancy, they also have croissants and cappuccino.


Grab a cookie and coffee, then hoon the loaner.

Definitely will, right after I put it in sport mode. I hate that they all seem to default to Eco+


Sorry that didn't help. About 1 hour of labor sounds about right. I hope that sorts it.

Not a problem! I appreciate the suggestion, always good to build a definitive list of what isn't the problem.

[daytona90t]

I tried something today to try to better understand the different driving modes that the DME is programed for. I drove to work in D mode and was able to create the 2,800 rpm stumble every time. It is very noticeable in D. I drove half way home in S mode and the stumble is still there but much less pronounced. I drove the rest of the way in M mode and was able to floor it and click through every gear without any stumble at all. I wonder if when in D and S mode the DME goes into a sort of high speed cruise mode for better fuel mileage and perhaps goes a little lean, and in M mode it is instead always ready for you to ask it for more, and not worried about fuel mileage, keeping the fuel maps the same as in lower gears. Just an observation and some ideas. My brain is incapable of not trying to figure this out.

[TheFinanceGuy]

Steve - let me how this goes. I'm having this issue as well right at the 2,800 mark. I've tried just about everything I can to get rid of it. Including sharking it!
My DME was updated according to my local tech. I honestly never thought about bring it to BMW of Sudbury for this.

BTW - will you be at their cars and coffee on May 7th?
http://www.herbchamberscarsandcoffee.com/

[anandoc]

I tried something today to try to better understand the different driving modes that the DME is programed for. I drove to work in D mode and was able to create the 2,800 rpm stumble every time. It is very noticeable in D. I drove half way home in S mode and the stumble is still there but much less pronounced. I drove the rest of the way in M mode and was able to floor it and click through every gear without any stumble at all. I wonder if when in D and S mode the DME goes into a sort of high speed cruise mode for better fuel mileage and perhaps goes a little lean, and in M mode it is instead always ready for you to ask it for more, and not worried about fuel mileage, keeping the fuel maps the same as in lower gears. Just an observation and some ideas. My brain is incapable of not trying to figure this out.

Your theory does make sense. I have similar observations - the 2800 stumble is less pronounced in M/S modes.

I feel that in the S mode, the gears are held longer and it downshifts much more readily as soon as you hit the gas, the stumble is less noticeable. Haven't really tried to drive much in M mode to reproduce this issue.

It might help if we have a member here with a automatic and the later DME version to chime in...

[terraphantm]

Your DME is already on the latest software. 7561382 refers to the "program" version and 7561520 is the "calibration". 7561382 is the newest program available, and the calibration is likely one of the ZHP-specific ones already.

[daytona90t]

Steve - let me how this goes. I'm having this issue as well right at the 2,800 mark. I've tried just about everything I can to get rid of it. Including sharking it!
My DME was updated according to my local tech. I honestly never thought about bring it to BMW of Sudbury for this.

BTW - will you be at their cars and coffee on May 7th?
http://www.herbchamberscarsandcoffee.com/

I bring both the zhp and the X3 to Sudbury for small stuff that I can't or don't want to do myself, like alignments and the occasional oil change. I have found that this helps keep a good rapport going for when I need things like a DME update. It's also nice to get to drive a loaner one and a while. I didn't buy either car from them but they have been great and treat me like I did.

I would like to go to the cars and coffee event, but I think that my wife has to work that morning and I doubt that I can get the 10 month old out of the house that early.

[daytona90t]

Your DME is already on the latest software. 7561382 refers to the "program" version and 7561520 is the "calibration". 7561382 is the newest program available, and the calibration is likely one of the ZHP-specific ones already.

If this is the case, do you know how to check the "calibration" version with either my handheld carsoft scanner or the P.A. Soft BMW scanner 1.4?

I was trying to use RealOEM to verify the latest version and this is what I was able to find.

For vehicles with Performance Package S767A=Yes
01 RMFD control unit DME programmed MS45.1 03/2003 07/2004 12147561520

12147561520
RMFD control unit DME programmed MS45.1

Supersedes:

12147542993 (09/01/2005 — 09/01/2005), Exchangeable retrospectively
12147549087 (09/01/2004 — 09/01/2005), Exchangeable retrospectively
12147548580 (08/01/2004 — 08/30/2004), Exchangeable retrospectively
12147547799 (07/01/2004 — 08/10/2004), Exchangeable retrospectively
12147546938 (07/01/2004 — 07/22/2004), Exchangeable retrospectively
12147537241 (03/29/2004 — 07/06/2004), Exchangeable retrospectively
12147540382 (12/01/2003 — 04/20/2004), Exchangeable retrospectively
12147537792 (12/01/2003 — 12/01/2003), Exchangeable retrospectively
12147536841 (08/01/2003 — 12/01/2003), Exchangeable retrospectively
12147533695 (07/01/2003 — 08/08/2003), Exchangeable retrospectively
12147532778 (05/01/2003 — 07/10/2003), Exchangeable retrospectively
12147531907 (02/21/2003 — 06/10/2003), Exchangeable retrospectively
12147531491 (03/01/2003 — 02/24/2003), Exchangeable retrospectively
12147530214 (03/01/2003 — 02/18/2003)

Part 12147561520 was found on the following vehicles:
3' E46   (09/1999 — 08/2006)

[TheFinanceGuy]

I bring both the zhp and the X3 to Sudbury for small stuff that I can't or don't want to do myself, like alignments and the occasional oil change. I have found that this helps keep a good rapport going for when I need things like a DME update. It's also nice to get to drive a loaner one and a while. I didn't but either car from them but they have been great and treat me like i did.

I would like to go to the cars and coffee event, but I think that my wife has to work that morning and I doubt that I can get the 10 month old out of the house that early.

Its a perfect for the baby! I used to bring them when they were little, not at 2 and 4 - they want to stay in bed - which I am not going to complain about!

I use a shop near me for the stuff, for the same reason. He is/was a BMW certified tech that opened his own shop.

[terraphantm]

If this is the case, do you know how to check the "calibration" version with either my handheld carsoft scanner or the P.A. Soft BMW scanner 1.4?

I was trying to use RealOEM to verify the latest version and this is what I was able to find.

For vehicles with Performance Package S767A=Yes
01 RMFD control unit DME programmed MS45.1 03/2003 07/2004 12147561520

12147561520
RMFD control unit DME programmed MS45.1

Supersedes:

12147542993 (09/01/2005 — 09/01/2005), Exchangeable retrospectively
12147549087 (09/01/2004 — 09/01/2005), Exchangeable retrospectively
12147548580 (08/01/2004 — 08/30/2004), Exchangeable retrospectively
12147547799 (07/01/2004 — 08/10/2004), Exchangeable retrospectively
12147546938 (07/01/2004 — 07/22/2004), Exchangeable retrospectively
12147537241 (03/29/2004 — 07/06/2004), Exchangeable retrospectively
12147540382 (12/01/2003 — 04/20/2004), Exchangeable retrospectively
12147537792 (12/01/2003 — 12/01/2003), Exchangeable retrospectively
12147536841 (08/01/2003 — 12/01/2003), Exchangeable retrospectively
12147533695 (07/01/2003 — 08/08/2003), Exchangeable retrospectively
12147532778 (05/01/2003 — 07/10/2003), Exchangeable retrospectively
12147531907 (02/21/2003 — 06/10/2003), Exchangeable retrospectively
12147531491 (03/01/2003 — 02/24/2003), Exchangeable retrospectively
12147530214 (03/01/2003 — 02/18/2003)

Part 12147561520 was found on the following vehicles:
3' E46   (09/1999 — 08/2006)


http://i.imgur.com/lXDjNvy.png

http://i.imgur.com/zxxtgNg.png

http://i.imgur.com/mmTLG7v.png

7561544 is the so-called "New Jersey" flash which is why mine shows that instead of 7561520 or 7561522. Nonetheless, if your DME is reporting 7561382 (notice that matches my "BMWTNR"), you're on the latest software.

[daytona90t]

Wow! That may be the most detailed response I have ever received on a forum, Thank you. I will check again this weekend and go into the "User info fields" to check my assembly number. I was honestly always terrified to drill into the "Reprogramming" under the DME section, lots of good info in there. Thanks again, I would hate to pay $145 for them to just tell me that I was already as up to date as possible.

[daytona90t]

Your DME is already on the latest software. 7561382 refers to the "program" version and 7561520 is the "calibration". 7561382 is the newest program available, and the calibration is likely one of the ZHP-specific ones already.

terraphantm is spot on with this stuff. I was able to locate the scanner log file from last week's scan and pull the User Info Fields.

This is what I have:

# USER INFO FIELDS
---------------------------------------------------------------------------------------------------------------------------
Unit Date Odometer Assembly Software Service Dealer Tester Program ver.
---------------------------------------------------------------------------------------------------------------------------
DME* -> 08.09.03 0 km 7.536.841 7.536.842 0.000.000 012321 42324 0044570LL00S
17.03.06 22800 km 7.561.520 7.561.521 0.000.000 012321 42324 0044570LO00S
EGS -> 08.09.03 0 km 7.535.062 7.535.063 1.000.000 012321 42324 -
23.07.08 76800 km 7.546.860 7.546.861 1.000.000 011111 12345 -

It looks like my DME was updated in 2006 to 7561520 and my EGS was updated in 2008 to 7546860.

So back to the drawing board with the 2,800rpm stumble issue.

[anandoc]

Thanks for posting this and thanks Terra (as always!) for the pointers.

Argh - I was hoping that the DMW update would be the fix. I wonder what else could be causing this...

[daytona90t]

Finally got a check engine light on my way into work this morning. Hopefully now I can pin point this issue. I also hope that it is something easy like an O2 sensor or coil packs. I am so busy over the next few months, I don't have time to really tear into something too complex. I will update when I am able to pull the code.

[daytona90t]

Pulled the code and got 2772 Tank Vent Valve: Activation. This seems to point to the Fuel Tank Breather Valve. I'm not sure if this is the cause of the problem or a symptom of the problem. I am also thinking that this could point to a greater issue with the CCV system. This is on my list of preventive maintenance projects but I just haven't gotten around to replacing it yet. As far as I know the CCV system on my car is original, but I don't have any of the usually described signs of a failed CCV such as oil usage or valve cover mayo. Does anyone know if a failed CCV or associated hoses could be the cause of the 2,800 rpm stumble and power loss? Has anyone ever had the 2772 code?

[anandoc]

I got my CCV and hoses replaced in 2014, along with VCG, OFHG, Fuel filter, fuel pump etc. None of these things helped me with the 2800 RPM issue.

[hcbeck2689]

I had a problem where my tank breather valve was constantly opening and closing. Indy couldn't figure out the problem and finally found an easy fix. Purge valve was disconnected.


Sent from my iPhone using Tapatalk

[ELCID86]

There are two purge valves. One on the engine and one on the charcoal can near gas tank. I replaced both and still had a (different) code. My issue was the vent valves near the fuel filler.

https://uploads.tapatalk-cdn.com/20170429/473f1718a5b39c89ea65c8b7cf22b5f9.jpg

https://uploads.tapatalk-cdn.com/20170429/5b141f930a61c60103d35dc6c586df37.jpg

[daytona90t]

I am thinking about keeping my appointment for Saturday to have the dealer check and update my DME software if necessary. I know that terraphantm verified that I am running the latest software but I am running out of ideas as to possible causes. I figure at best there will be a possible revision update and it will take care of the issue, and at worst I will be able to cross DME software issue off the list of possible causes. I will be out $145 but I would then be able to shift my focus towards O2 sensors, coil packs, etc. I hate throwing money at an issue when I am not 100% sure of the cause, but again, I am running out of ideas.

Also, I cleared the 2772 Tank Vent Valve: Activation code and it hasn't come back after about 100 miles.

[az3579]

I hate throwing money at an issue when I am not 100% sure of the cause, but again, I am running out of ideas.



This is when that $145 is better spent on proper diagnosis by a shop that knows what they're doing. If you're on the latest software, the dealer isn't going to be able to help you, and all you did was donate money and get nothing in return.

[ELCID86]

I'd agree. Find a good Indy shop and pay the 1-2 hours of labor for diagnosis.

[Tunes]

I had this issue with mine and it was the coil. Changed them all and its all good.

[ELCID86]

^ hadn't thought of that. 6 new coils may be in order :dunno

[daytona90t]

I just canceled the appointment for the dealer since the DME re-flash seems to be pointless. I am going to re-set my adaptations and see if that has any effect. I need to put together a better diagnostic system than just the carsoft scanner or the P.A. Soft BMW scanner 1.4. I really want to be able to check everything such as DISA and VANOS function, spark advance, and O2 values in real time.

Without any codes other than the 2772 Tank Vent Valve I don’t have much to go on. As suggested by ELCID86, I am going to check my fuel vapor components in the rear wheel well. If I can’t detect any physical issues or a vacuum leak, I will replace the vent valve. I am already planning on replacing the entire CCV system and the coil packs this summer as part of my 100,000 mile preventive maintenance. I will keep you all posted of any updates, developments or solutions.

[daytona90t]

I finally got some time to work on the car this weekend and got a ton of stuff done, unfortunately none of it remedied the 2,800 rpm hesitation issue. I replaced me entire CCV system with the OEM cold climate version, not as bad of a job everyone makes it out to be. While in there I also inspected and cleaned the throttle body, idle control valve, and DISA, rebuilt a few years back with the G.A.S. kit and still looks good. I also replaced all 6 coil packs with new Bosch ones and replaced the fuel tank vent valve. To finish off I checked fuel pressure at the rail, a nice 55 psi at idle, and reset DME adaptations.

I am not too upset as all of the above was either part of my planned 100,00 mile preventive maintenance for this summer, or it was to address the check engine light and 2772 code that I was getting. The other labor, inspection, and cleaning, was also piece of mind. The only things left on my list of possibilities are a failed VANOS solenoid, O2 sensors, or software issue. Without any codes I cant be sure.

With that said, I guess that I am back to square one with the hesitation issue. I need to put it out of my mind for a few weeks, as I am now going to be busy through the rest of June with work, fathers day, and my daughter's first birthday party. I will need a state inspection in July and while at the dealer I may see what, if anything I can have them do for a diagnosis, and perhaps have them see if it is possible that there is still a software related issue, even though I should have the latest software revisions.

[anandoc]

Have you rebuilt the VANOS seals? Slater helped do my VANOS seals a few weeks ago and I am pretty sure that the 2800 hesitation got better after that. Mind you, I still have a hesitation but its not as terrible as it used to be before the VANOS rebuild.

[slater]

Have you rebuilt the VANOS seals? Slater helped do my VANOS seals a few weeks ago and I am pretty sure that the 2800 hesitation got better after that. Mind you, I still have a hesitation but its not as terrible as it used to be before the VANOS rebuild.

i don't think it's related to VANOS as i didn't develop the 2500-3000rpm stumble until well after rebuilding the VANOS in my car. it's gotta be something else... something perhaps not obvious.

i know shawn said unplugged the DISA cured it for him (i think i remember that correctly?), and the later/latest BMW DME code fixes it, but also doesn't it disable the operation of the DISA? just thinking out loud here.

[daytona90t]

Have you rebuilt the VANOS seals? Slater helped do my VANOS seals a few weeks ago and I am pretty sure that the 2800 hesitation got better after that. Mind you, I still have a hesitation but its not as terrible as it used to be before the VANOS rebuild.

Hi,

Yes I actually rebuilt the VANOS last fall with the Beisan Systems seal and rattle repair kit. After the VANOS rebuild I definitely felt more power and better throttle response. The 2,800 rpm hesitation that I am experiencing didn't begin until about 3 months ago, about 6 months after I rebuilt the VANOS. I am thinking about possible VANOS solenoid issue though. In hind sight I think I would have been better of going with the Dr. VANOS rebuild. It's not that rebuilding the VANOS was difficult, but I am fairly sure that Dr. VANOS also cleans, inspects, tests, and warranties the whole unit, including the solenoids.

[daytona90t]

i don't think it's related to VANOS as i didn't develop the 2500-3000rpm stumble until well after rebuilding the VANOS in my car. it's gotta be something else... something perhaps not obvious.

i know shawn said unplugged the DISA cured it for him (i think i remember that correctly?), and the later/latest BMW DME code fixes it, but also doesn't it disable the operation of the DISA? just thinking out loud here.

It seems to be the consensus that my car has the latest software versions. My DME was updated in 2006 to 7561520 and my EGS was updated in 2008 to 7546860. I can verify with my scan tool that at 4,000 rpms on the nose, my intake changes from long pipe to short pipe, or DISA going from closed to open.

[daytona90t]

This past week I had the car at my local dealer for an alignment and state inspection. Since it was already there I asked them to check my DME calibration version and to verify that it was in fact the latest and final version for my car. DME calibration 7.561.520, 7.561.521 is the latest and final version for my car. Incidentally, even though I asked them only to check and verify the version and update if a newer calibration version was available, they went ahead and reloaded the same version anyway. This had absolutely no affect on the 2,800 rpm hesitation issue!

Since I asked for an update and not for the same version to be reloaded, I wasn't very happy when they tried to charge me for it. Based on the perceived miscommunication we worked something out so that I am not completely out of pocket for a service, but that is another story.

If you already have the latest calibration, a possible software update to fix this issue can be crossed off the list. It will have no affect. If you can verify that you have an older software calibration, there may be some hope. As for me, I am back to the drawing board.

[anandoc]

Thanks for the update.

And the search continues...

[ELCID86]

i don't think it's related to VANOS as i didn't develop the 2500-3000rpm stumble until well after rebuilding the VANOS in my car. it's gotta be something else... something perhaps not obvious.

i know shawn said unplugged the DISA cured it for him (i think i remember that correctly?), and the later/latest BMW DME code fixes it, but also doesn't it disable the operation of the DISA? just thinking out loud here.

Yes. Left unplugged for a few days then back in. For some odd reason it did. I still have a bit of a stumble every once in a while but not very often.

[daytona90t]

Quick update! I finally got a DME code today that I was able to see with BMW Scanner 1.4. The code is 2960[10592] O2-Sensor Before Kat Bank1. Apparently this is a code that many get before updating to the latest DME software. Since I have the latest DME software for my car and this code came up after I had the software flash done last month, I am going to go ahead and replace both pre-cat O2 sensors.

For the past few weeks my theory has been that if so many have remedied the 2,800 rpm stumble by having their DME software update to the latest version, and if the latest software revision recalibrates the DME to read the O2 sensors in a wider range; since the update didn't work for me, at least one of my O2 sensors must be failing and out of range. Now that I have a code suggesting just this, and my car now has 107,000 miles on it, I think that it is worth replacing the O2 sensors

I am currently using the (Mike's Easy BMW Tools) thread in the coding section to put together a diagnostic machine running INPA. With this I would be able to definitively check the O2 sensors and see if they are reporting out of range. Based on how this has been going, I can easily get 2 new O2 sensors in the car before I get the cable in from Amazon and figure out the BMW Tools software install.

I will report back once the new O2 sensors are in, probably next weekend.

[anandoc]

Thanks for the update. I installed 2 new Bosch pre-cat O2 sensors back in 2015 because I used to get the codes too (along with a check engine light). The codes went away for a while but I still get them sometimes...especially when I am in cruising speeds.

[daytona90t]

Upon digging further and further into the depths of internet auto forums it seems that this issue plagues not only the M54 but also the S54 engine. I just read through this entire M3Forum.net post (The M3 got hickups (http://www.m3forum.net/m3forum/showthread.php?t=238574)) and there is some good conversations in there, but just like all of the other forum discussions, no definitive solutions.

[ELCID86]

^i didn't realize that. :-(

[daytona90t]

It seems that I have finally had success at solving this issue. I replaced both pre-cat O2 sensors this morning with the Bosch 17215, re-set DME adaptations, and took the car for a drive. The car seems to be completely cured of the 2,800 rpm stumble/hesitation issue and feels more responsive and eager to pull all the way through the rev range than I have ever experienced. After 6 months of researching, replacing a bunch of parts, and verifying that I already had the most up to date DME software revision, it seems to have been a degraded pre-cat O2 sensor all along. I never had a check engine light, or even a code until last weekend.

Hopefully my experience can help someone else on here from going completely insane trying to cure this issue. If you have had your DME updated, or verified that you already have the most up to date software revision, and even if you don't have a code indicating a bad O2 sensor, replace your pre-cat O2 sensors.

[anandoc]

Thanks for continuously updating this thread.

So I guess in my case, I need the updated DME software to solve this since I replaced my pre-cat O2 sensors with the Bosch ones in 2015. I also have a GAS modified DISA valve.

[holyc0w]

It seems that I have finally had success at solving this issue. I replaced both pre-cat O2 sensors this morning with the Bosch 17215, re-set DME adaptations, and took the car for a drive. The car seems to be completely cured of the 2,800 rpm stumble/hesitation issue and feels more responsive and eager to pull all the way through the rev range than I have ever experienced. After 6 months of researching, replacing a bunch of parts, and verifying that I already had the most up to date DME software revision, it seems to have been a degraded pre-cat O2 sensor all along. I never had a check engine light, or even a code until last weekend.

Hopefully my experience can help someone else on here from going completely insane trying to cure this issue. If you have had your DME updated, or verified that you already have the most up to date software revision, and even if you don't have a code indicating a bad O2 sensor, replace your pre-cat O2 sensors.

That sounds more like the DME adaptation reset.

[daytona90t]

That sounds more like the DME adaptation reset.

No, it wasn't just the DME adaptation reset. I have been chasing this issue for 6 months and have reset DME adaptations a number of times myself, plus the DME re-flash that I had done at the dealer 6 weeks ago wiped the entire DME and reloaded the latest software revision. None of the previous adaptation resets or the DME re-flash had any effect.

[BMWCurves]

Cool, thanks for following up!

If you can, you might consider cataloguing all your attempts at fixing the issue plus the final solution in your original/first post so other people can find your solution quickly!